The detection of early stages of stress corrosion cracking initiation has been a subject of great interest to the corrosion community, particularly to those in the nuclear industry. Such early detection of cracking would enable one to take corrective action before the occurrence of major component failures. Particularly in a nuclear reactor, it is highly desirable and imperative to prevent major component failure.
The most commonly known stress corrosion cracking detection approach is to use a constant extension rate tensile (CERT) test. In a CERT test, a dog bone type tensile specimen is stressed at a constant extension rate within an autoclave containing the corrosive environment. The test is interrupted at known % strains, and at each interruption, the specimen is examined for crack initiation. The crack initiation process has been studied, using CERT tests, as a function of water temperature, heat treatment temperature, cold work, etc.
Although CERT tests provide very valuable information, a shortcoming of the CERT test technique is the need to periodically remove the specimen from the high temperature autoclave for microscopic examination to detect the initiation of stress corrosion cracks. Removing and inspecting the specimen adds time and expense to the testing operations. In addition, the CERT test approach cannot be used as an in-situ tool for the early detection of stress corrosion cracks in the environment.
It would be desirable to prevent major component failure due to stress corrosion cracking by early detection of the initiation of such cracking. It also would be desirable to provide an in-situ method and device for crack detection in a reactor and other environments.